In a computing device to computing device group communication using a radio interface technology it may be that some users cannot directly communicate with other users, perhaps due to range restrictions, but they may be able to communicate with computing devices in between. These computing devices could relay the communication to complete the connection between users that otherwise could not directly communicate.
FIG. 1 illustrates an example of a communication group with a common interest where not all users via their computing devices UEa . . . UEn can communicate directly with each other. The particular problems posed by this scenario include:                The individual users can move so the links can change, break or make. This means a heavy protocol or centralized approach would not be ideal. A heavy protocol may be too slow to adapt to the changing environment. Any controlling entity in a centralized approach may itself lose communications and so the group may take some time to re-establish.        When one user computing device transmits, a receiving user computing device may need another computing device to relay the communications, but this receiving user computing device does not always need relaying from the same relaying user computing device. Other users may be receiving directly or require relaying from different computing devices.        The link quality needs to be maintained but the more transmitting relays, the more interference they generate. The ideal solution will minimize the number of computing devices relaying but preserve good link quality.        
The 4G (LTE) radio access technology is being adopted by Public Safety Communications organizations around the world, initially United States and United Kingdom. They have requirements to add group communications and computing device to computing device capability. They also want the ability to relay between computing devices and from computing devices into the network where necessary.
Present invention has come about following some initial work to propose a Floor Control approach for group communications and using the basis of that protocol to assist with relaying. Three documents were submitted, by the inventor of present invention, to 3GPP SA2 for this problem (3GPP S2-143315, S2-144292, S2-144293).
On another hand, U.S. Pat. No. 7,551,562 discloses an optimum routing approach over a mesh network that can take account of link quality of other component links in a chain by signalling the quality of the other link(s). What this does not address is (i) the multi-source/group destination nature in this present invention and (ii) the other routing optimisations for a radio network such as minimising the number of relaying computing devices or actively seeking the minimum number of hops so long as, in both cases, adequate link performance is maintained.
Existing solutions have mainly dealt with mesh solutions to achieve point to point communications mostly assuming a routing choice based on seeking a connection route into the wider internet network for each individual device. This has a limited one way nature to it and doesn't consider either (i) the case where many recipients wish to receive the same communication thus permitting optimizations where one computing device can relay communication for several others in advantage to each computing device being provided with an optimum link to a network gateway and (ii) because there are multiple source and destination computing devices, different relay optimizations may apply for each user for different transmitting computing devices.